Dual trailer

ABSTRACT

A dual dump trailer assembly ( 10 ) is provided which provides for operating two end dump trailers ( 12, 14 ) with a single cab ( 16 ). The operation is possible by use of a movable pedestal ( 30 ) having a fifth wheel mounted on the forward end dump trailer ( 12 ). The pedestal ( 30 ) is in the rearward, trailing position to attach the rearward end dump trailer ( 14 ) at the fifth wheel ( 110 ) on the pedestal for towing. Upon arrival at the dump site, the rearward end dump trailer ( 14 ) can be dumped and then detached from the forward end dump trailer ( 12 ). The pedestal ( 30 ) mounting the fifth wheel will move forward to a forward, dumping position, permitting the contents of the forward end dump trailer ( 12 ) to be dumped.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/297,757 filed Jan. 21, 2000, now U.S. Pat. 6,257,669 B1 issued Jul.10, 2001 which claims priority from PCT Application PCT/US98/18470 filedSep. 4, 1998 which claims priority-from Provisional Application Ser. No.60/058,071 filed Sep. 5, 1997.

TECHNICAL FIELD OF THE INVENTION

This invention relates to payload bearing vehicles, and in particular todump trailers.

BACKGROUND OF THE INVENTION

In hauling materials over the highways, particularly materials withindump trailers, there is a conflict between the desire to carry as muchmaterial as possible and weight limitations regulating the gross weightof a highway vehicle established in many jurisdictions within the UnitedStates and foreign countries. The gross weight permitted under law istypically related to the vehicle size, and particularly to the vehiclewheel base. In particular, the gross weight permitted is often relatedto the number of axles on the vehicle and the wheel base defined as thedistance between selected axles. In the common semi-trailer typeconfiguration including a power unit and a trailer, the wheel base canbe measured a number of ways. The wheel base can be measured between theleading and trailing axles of the trailer, between the leading driveaxle of the power unit and the trailing axle of the trailer or betweenthe steering axle of the power unit and the trailing axle of thetrailer.

A need continues to exist for optimizing the load carrying capability ofa vehicle while complying with the relevant laws governing vehicleweight. By carrying fewer, heavier loads, the operator can save expensesas well as reduce impact in neighborhoods by passage of the vehicles.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a dual dumptrailer assembly is provided which includes a cab, a first end dumptrailer for attachment to said cab with the first end dump trailerhaving a pedestal for movement between a forward, dumping position and arearward, towing position and a second end dump trailer for attachmentto said first end dump trailer at the pedestal in the rearward, towingposition. In accordance with another aspect of the present invention,the pedestal on the first end dump trailer mounts a fifth wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the invention and its advantages willbe apparent from the following detailed description when taken inconjunction with the accompanying drawings, in which:

FIG. 1A is a side view of a dual dump trailer assembly forming a firstembodiment of the present invention illustrating the rear dump trailerin dumping position;

FIG. 1B is a side view of the dual dump trailer assembly illustratingthe rearward end dump trailer removed from attachment to the pedestal onthe front end dump trailer after having dumped its load;

FIG. 1C illustrates the dual dump trailer assembly with the pedestal onthe forward end dump trailer moved into the forward, dumping position;

FIG. 1D illustrates the forward end dump trailer moved into the dumpingposition;

FIG. 1E illustrates the dual dump trailer assembly with the rearward enddump trailer attached to the pedestal of the forward end dump trailer sothat the dual dump trailer assembly can be driven down the highway;

FIG. 1F is a side view of the cab and forward end dump trailerillustrating the pedestal in the forward, dumping position;

FIG. 2 is a side view of the cab and forward end dump trailer with thepedestal in the rearward, towing position;

FIG. 3 is a side view of the cab and forward end dump trailer with thetrailer body in the tilted position for dumping the payload;

FIG. 4 is a side view of a portion of the forward end dump trailerillustrating the wedge structure;

FIG. 5 is a top view of a portion of the forward end dump trailer alongline 5—5 in FIG. 4 to illustrate the locking structure;

FIG. 6 is a vertical cross section in the forward end dump trailer takenalong line 6—6 in FIG. 4;

FIG. 7 is a side view of a cab and a frame type forward end dump trailerwith the pedestal in the rearward position for towing forming a firstmodification of the present invention;

FIG. 8 is a side view of the cab and the frame type forward end dumptrailer illustrating the pedestal in the forward position for dumpingoperation;

FIG. 9 is a side view of a portion of the frame type forward end dumptrailer;

FIG. 10 is a cross-sectional view of the frame type forward end dumptrailer taken along line 10—10 in FIG. 9; and

FIG. 11 is a plan view of the locking mechanism of the frame typeforward end dump trailer.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views, andin particular to FIGS. 1A-1E, a dual dump trailer assembly 10 isillustrated which provides for operating two end dump trailers, aforward end dump trailer 12 and rearward end dump trailer 14, with asingle cab or power unit 16. At least the forward end dump trailer 12 isprovided with a pedestal 30 which can be moved on the forward end dumptrailer 12 between a forward, dumping position and a rearward, trailingposition. While trailering both end dump trailers, the pedestal 30 is inthe rearward position as illustrated in FIG. 1E, allowing the rearwardend dump trailer 14 to be towed thereby. Rearward end dump trailer 14attaches to a fifth wheel 110 forming part of the pedestal 30 fortowing. When dumping, the rearward end dump trailer 14 is dumped first,as seen in FIG. 1A. The rearward end dump trailer 14 is then removedfrom the assembly as seen in FIG. 1B. The pedestal 30 is moved forwardrelative the rest of the forward end dump trailer 12 until the pedestalis in the forward position completely underneath the forward end dumptrailer 12 and forward of the end of the forward end dump trailer 12 asseen in FIG. 1C to allow the forward end dump trailer to be dumped, asseen in FIG. 1D.

While the rearward end dump trailer 14 does not require a slidingpedestal 30, it is preferred that the trailers 12 and 14 are identicaland therefore interchangeable in the role of the forward or rearward enddump trailer. However, if desired, rearward end dump trailer 14 can beany style of end dump trailer suitable for attachment to fifth wheel110. A sliding pedestal 30 of the type contemplated is disclosed in thepresent inventor's prior issued U.S. Pat. No. 531,753 issued Jul. 30,1985, U.S. Pat. No. 4,660,843, issued Apr. 28, 1987, and U.S. Pat. No.4,865,341, issued Sep. 12, 1989. All three patents are incorporated byreference herein in their entirety.

With reference to FIG. 1F and FIG. 2, additional details of the cab 16and forward end dump trailer 12 will be described. The rearward end dumptrailer 14 can be identical to forward end dump trailer 12 and thereforeneed not be described. The forward end dump trailer 12 is a framelessstyle. The end dump trailer 12 is in the horizontal position shown inFIGS. 1F and 2 during loading of the payload and while traveling on thehighway. When the payload is to be dumped, a hydraulic mechanism in theforward end dump trailer 12 will pivot the trailer body 17 to an angleup to approximately 50 degrees from the horizontal to dump, as seen inFIG. 3.

As set forth in the background of the invention, local jurisdictionshave restrictions on gross vehicle weight based on certain lengthsbetween axles on a vehicle. The trailer assembly 10 illustrated has asteering axle 20 and forward and rearward drive axles 22 and 24 on thecab 16. Forward end dump trailer 12 has a forward trailing axle 26, amiddle trailing axle 27 and a rearward trailing axle 28, while therearward end dump trailer 14 also has a forward trailing axle 26, amiddle trailing axle 27 and a rearward trailing axle 28. The axles 26,27 and 28 are part of rear wheel unit 18 which is mounted to pedestal30. The various distances between these axles can be optimized, partlyby providing for the appropriate position of the pedestal 30 in therearward, towing position, to provide an optimal load for the givenweight restriction laws in a particular jurisdiction.

In the normal construction of an end dump trailer, the rear wheel unit18 must be positioned relative to the body as illustrated in FIGS. 1Fand 3 to permit the trailer body 17 to pivot upward for dumping of thepayload. If the rear wheel unit 18 was permanently mounted behind thedumping lift 100 of the trailer body 17 seen in FIG. 3, a protectiveshield or ramp would be required to protect the unit 18 from damage fromthe payload during dumping. Also, the maximum dumping angle of thetrailer body 17 generally decreases as wheel unit 18 is positionedfurther back on the trailer 12.

In accordance with the teachings of the present invention, the pedestal30 supporting the rear wheel unit 18 on the forward end dump trailer 12is slidable along a portion of the length of the trailer between theforward, dumping position shown in FIGS. 1F and 3 and the rearward,towing position shown in FIG. 2. By sliding the pedestal 30 into therearward, towing position, the wheel base X on the dump trailer assembly10 has been increased.

With reference to FIGS. 4 and 6, the pedestal 30 slidably contacts thebottom of channels 32 forming part of the frame 33 of the trailer body17 and located on either side of the trailer body. Polyethylene pads 34are bolted to the surface 36 of the pedestal 30 by bolts 37 proximatethe channels 32 to reduce friction between the trailer body 17 andpedestal 30 and also to provide a cushioning action between the twoelements.

Forward frame wedges 38, middle frame wedges 40 and rearward framewedges 42 are positioned on either side of the trailer body 17 on thechannels 32. The frame wedges 38, 40 and 42 cooperate with the forwardpedestal wedges 44 and rearward pedestal wedges 46. In the forwardposition of pedestal 30 shown in FIGS. 1F and 3, the forward pedestalwedges 44 engage the forward frame wedges 38 and the rearward pedestalwedges 46 engage a portion of the middle frame wedges 40. In therearward position illustrated in FIGS. 2 and 4, the forward pedestalwedges 44 are engaged with a portion of the middle frame wedges 40 andthe rearward pedestal wedges 46 are engaged with the rearward framewedges 42 to wedge the pedestal to the frame 33 in the rearwardposition.

A forward locking assembly 48, shown in FIG. 5, is mounted on frame 33and cooperates with locking holes 50 formed in the pedestal 30 as shownin FIG. 4. The forward locking assembly 48 comprises a dual doubleacting cylinder 52 having pistons 54 and 56 shown in their retractedpositions in FIG. 5. Locking wedges 58 and 60 are positioned at the endof pistons 54 and 56, respectively. When the pedestal is moved into theforward position by locking the brakes on the rear wheel unit 18 of theforward end dump trailer 12, and backing the cab 16, the pistons 54 and56 can be activated to drive the locking wedges 58 and 60 into thelocking holes 50. The wedges 58 and 60 have wedge surfaces 62 which actto wedge the pedestal wedges into the frame wedges when the pistons 54and 56 move outwardly from the dual cylinder 52. In the forwardposition, the dual dump trailer assembly 10 is adapted for the dumpingof the payload of the forward end dump trailer 12.

A rearward locking assembly 66 is also mounted on the frame 33. Therearward locking assembly 66 comprises the identical elements of forwardlocking assembly 48 but with the wedge surfaces 62 oriented in thedirection opposite those in the forward locking assembly 48. To move thepedestal 30 into the rearward position, the brakes on unit 18 are againlocked and the cab 16 is moved forward. The rearward locking assembly 66will act to wedge the pedestal wedges into the frame wedges when thepedestal 30 is in the rearward position for travel on a public highway.

The pedestal 30 is aligned with the frame 33 by polyethylene blocks 68having guide surfaces 70 as best shown in FIG. 6. The blocks 68 aresecured to angle members 72 which are bolted to a flange 74 on each sideof the frame 33 as best seen in FIG. 6. The angle members 72 and blocks68 can be adjusted inwardly toward the pedestal or outwardly from thepedestal by adjusting screws 76. Typically, a small gap 78 will bemaintained between the guide surfaces 70 and the pedestal 30. Thepolyethylene blocks 68 will maintain the pedestal 30 aligned with theframe 33 both in the forward and rearward positions and while movingbetween the positions.

In the preferred construction, the dual cylinders 52 in both the forwardand rearward locking assemblies 48 and 66 are double acting and operatedby air pressure. This will permit the locking assemblies to be operatedby the vehicle operator from within the cab 16.

The assembly 10 described above and illustrated in FIGS. 1-6 is commonlyreferred as having frameless end dump trailers, as the main frame andthe trailer body of end dump trailers 12 and 14 are integral. FIGS. 7-11illustrate a dual dump trailer assembly 200 which incorporates a frametype forward end dump trailer 202 and a rearward frame type end dumptrailer 203 (not shown but identical to forward frame type end dumptrailer 202). However, in all other respects, the assembly 200 operatesin the same manner as assembly 10. Forward frame end dump trailer 202 isidentical to trailer 203, and only trailer 202 will be described. Thetrailer 202 includes a separate horizontal rigid frame 204 which isattached at its forward end to the cab 16 and a trailer body 206 whichis pivoted near the dumping end of the rigid frame 204 for pivotalmotion between a horizontal traveling position, as shown in FIG. 7, anda tilted dumping position as shown in FIG. 8.

The trailer 202 is provided with a pedestal 208 which performs theidentical function of pedestal 30 discussed previously in permittingdumping of the trailer body 206 when in the forward position shown inFIG. 8 and for trailering when in the rearward position shown in FIG. 7.

As best seen in FIG. 10, the pedestal 208 slidably contacts the bottomof channels 210 forming part of the frame 204. Polyethylene pads 212 arebolted to the upper surface 214 of the pedestal 208 to reduce frictionbetween the trailer frame 204 and pedestal 208 and also to provide acushioning action between the two elements. An adjustable side bearing216 is mounted on the pedestal by a threaded bolt 218. The threaded bolt218 can be rotated to move the side bearing 216 into contact with theside of the frame 204 to insure the pedestal will slide along the lengthof the frame without jamming.

As best seen in FIG. 9, the trailer 202 includes forward frame wedges220, middle frame wedges 222 and rearward frame wedges 224 positioned oneither side of the frame 204 on the channels 210. The pedestal 208 isprovided with forward pedestal wedges 226 and rearward pedestal wedges228 on either side of pedestal 208. When the pedestal 208 is in theforward position, the forward pedestal wedges 226 engage the forwardframe wedges 220 and the rearward pedestal wedges 228 engage a portionof the middle frame wedges 222. In the rearward position, illustrated inFIG. 9, the forward pedestal wedges 226 engage a portion of the middleframe wedges 222 and the rearward pedestal wedges 228 are engaged withthe rearward frame wedges 224.

With reference to FIG. 11, the locking assembly 230 is illustrated. Thelocking assembly 230 is mounted on the pedestal 208 and includes an aircylinder 232 having a piston 233. A pivot plate 234 is pivotally mountedto the pedestal at pivot 235 and to the end of the piston 233. Lockingwedge 236 is connected to plate 234 by a pivotal link 238. A secondpivot plate 240 is pivoted to the pedestal and connected to the plate234 by a pivotal link 242. The opposite locking wedge 244 is connectedto plate 240 by a pivotal link 246. As can be seen, when air is providedto cylinder 232 to extend the piston 233, the wedges 236 and 244 areretracted. When air is provided to the cylinder to retract piston 233,the wedges extend outwardly for locking the pedestal either in theforward position against the forward lock plate assemblies 248 or in therearward position with rear lock plate assemblies 250. In operation, thevehicle 200 is an identical manner to the dump trailer assembly 10described hereinabove.

Although several embodiments of the present invention have beenillustrated in the accompanying drawings and described in the foregoingdetailed description, it will be understood that the invention is notlimited to the embodiments disclosed, but is capable of numerousrearrangements, modifications and substitutions of parts and elementswithout departing from the scope and spirit of the invention.

What is claimed is:
 1. A method for operating a dump trailer assembly,comprising the steps of: attaching a first end dump trailer to a cab,said first end dump trailer having a pedestal for movement between aforward, dumping position and a rearward, towing position; attaching asecond end dump trailer to the pedestal of the first end dump trailerwhen the pedestal is in the rearward towing position; and towing thefirst and second end dump trailers simultaneously with said cab.
 2. Themethod of claim 1 further comprising the step of dumping contents of thesecond end dump trailer and thereafter removing the second end dumptrailer from the first end dump trailer.
 3. The method of claim 2further comprising the step of dumping contents of the first end dumptrailer after the second end dump trailer has been detached therefrom.